This invention relates to headlight lamp units of the sealed beam type for automotive vehicles.
Safe operation of automotive vehicles during night time driving often requires changes in the intensity and angular position of the light beams emitted from the headlight lamp units of the vehicle. At the present time, light beam position is adjustable under driver control during vehicle movement between a very limited number of positions. The lamp units must accordingly be mounted in a fixedly adjusted position selected as a compromise in accomodating different road conditions and highway geometry. In view of the advantages associated with the sealing of the lamp filaments in the reflector chamber of the lamp unit, driver controlled adjustment of the filament position has not been seriously considered as a solution to the problem. It is therefore an important object of the present invention to provide for adjustment of filament position within a sealed type lamp unit under driver control in order to meet varying road conditions during night time driving.
In accordance with the present invention, at least two lamp filaments are carried on the forward end of an elongated filament assembly which is pivotally mounted within a lamp unit housing by a spherical bearing. The forward end of the filament assembly is exposed to the inert atmosphere sealed within the reflector chamber by a bellows arrangement to accomodate pivotal displacement of the rear end of the filament assembly by a high reduction gear ratio adjusting mechanism. The angular movement of the adjusting mechanism is measured by an adjustable potentiometer to enable the driver to detect adjustment of the light beam through a dash-mounted indicator assembly. A heat shield protectively separates the sealed reflector chamber of the lamp unit from the operating chamber enclosing the motor driven adjusting mechanism. Pivotal movement of the filament assembly along a plane at an angle to the vertical is guided by a guide slot in the heat shield through which the filament assembly extends. In this fashion, the light beam in its lower level positions is directed laterally toward the curb for illuminating pedestrians.